This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We propose to provide an omega-6 predominant lipid infusion (Omegaven) to patients with severe parenteral nutrition associated cholestasis (conjugated bilirubin >6) on a compassionate use basis. We will monitor for safety parameters during the maximum 5 months of intervention. The Omegaven will be intravenously infused at a dose of 1gm/kg/day until the infant is weaned from parenteral nutrition and for no longer than 5 months. This is a continuation of protocol H-21344. To provide a mechanism for critically ill infants with parenteral nutrition (PN) associated cholestasis to receive Omegaven for compassionate use situations for which there are no satisfactory alternative treatments. Parenteral nutrition (PN) provides intravenous nutritional supplementation for patients unable to absorb adequate enteral nutrients secondary to insufficient intestinal length or function. PN contains the macronutrient building blocks of the human diet in their most elemental forms (amino acids and dextrose) and is commonly administered with a lipid emulsion to avoid essential fatty acid deficiency and to provide a calorically dense source of non-protein calories. In addition, PN contains the essential micronutrients (electrolytes, trace elements, and vitamins) to provide an optimal nutritional regimen. Before the development of PN in the late 1960 s, patients with insufficient gastrointestinal absorptive function commonly died of starvation and subsequent complications of malnutrition (1, 2). Today, more than 30,000 patients are permanently dependent on parenteral nutrition for survival. However, PN continues to be associated with hepatic injury that occurs at an unpredictable rate and includes both biochemical, i.e., elevated serum aminotransferase and alkaline phosphatase, and histologic alterations such as steatosis, steatohepatitis, lipidosis, cholestasis, fibrosis, and cirrhosis (3, 4). These abnormalities, which may worsen with the duration of PN administration, is more prevalent in the pediatric population. Additional risk factors for this condition include prematurity, low birth weight, long-term use of PN, the lack of concomitant enteral intake, sepsis, and multiple operative procedures (5).